Almost everyone knows that our blood transports oxygen and nutrients for the body’s cells and flows in arteries and veins – but in addition, there is a second liquid transport system. Although it does not contain as much fluid as the bloodstream, it is all the more important for the immune system and the removal of waste products. We are talking about the lymphatic system, which uses lymph to supply human cells with vitamins, nutrients and fats.
Lymphatic system and lymph: what exactly is it?
The lymphatic system includes lymph and lymphatic vasculature on the one hand, and lymphatic organs on the other hand, which produce certain defense cells (lymphocytes) and change them according to the requirements. When our blood flows through the smallest arteries and capillaries back into the smallest veins, some fluid always remains between the cells. This tissue fluid supplies our cells with vitamins, nutrients and fats. Conversely, cells release degradation products and cellular waste into this fluid, and pathogens and foreign substances are also removed from the cells in this way.
Up to 2 liters of this fluid are produced per day, it is light yellow in color and is called lymph. This fluid, which is enriched with harmful substances, is not released directly back into the blood, but is transported in its own vascular system and filtered in intermediate control stations, the lymph nodes, and examined for pathogens.
Lymphatic vascular pathways in the lymphatic system
Because the lymph nodes store a large proportion of our defense cells, the lymphocytes, they are alerted to contact with pathogens, multiply, and can prevent the spread of pathogens. The lymphatic pathways run parallel to the veins of the body, beginning as the smallest lymphatic vessels in the tissues and merging into progressively larger lymphatic pathways. The largest lymphatic pathway ends above the heart in the superior vena cava and is called the thoracic duct.
While smaller lymph nodes are incorporated into the vascular system, there are larger collections of lymph nodes in the inguinal and axillary regions, the neck, and the abdomen, where the collected lymph is filtered. From there, it is then transported further in larger vessels.
Function of the lymph
Interestingly, the lymph also has the function of absorbing all the dietary fats in the abdomen. After a high-fat meal, the lymph fluid from the gastrointestinal tract is no longer clear and transparent, but milky and cloudy due to the high fat content. A large proportion of the dietary fats are thus bypassed by the liver, so they do not enter the blood and reach all the cells as a source of energy. If the liver were to be contacted prematurely, it would immediately break down and convert the dietary fats, and this important source of energy would be lost to the cells.
In addition to the lymph nodes, the lymphoid organs include the spleen, bone marrow, thymus, tonsils, and other lymphoid follicles (collections of lymphocytes in the intestinal mucosa or appendix).
